Palladium-catalyzed para-selective arylation of phenols with aryl iodides in water

Abstract

Highly para-selective palladium-catalyzed direct arylation of phenols with aryl iodides was demonstrated by taking advantage of the formal inverse direct arylation strategy. A series of 4-aryl phenols were synthesised by employing water as a "green" solvent under mild reaction conditions.

Rhodium-catalyzed synthesis of quinolines and imines under mild conditions

“…Thus, the developed protocol sounds to be highly efficient for the synthesis of quinolines and imines. 25 …”

“…1 Furthermore, substituted quinoline structural frameworks are often found in many biological active molecules and they exhibits antibacterial, 2 antimalarial, 3 antiinflammatory, 4 antiprotozoan, 5 20 antiasthmatic, 6 antituberculosis, 7 antihypertensive, 8 anticancer, 9 anti-HIV, 10 and antihelmintic activities. 11 Moreover, quinolines are also vital synthons for the synthesis of many important materials such as nano-meso structures and polymers which are investigated for applications in electronics, optoelectronics and 25 nonlinear optics. 12 Hence, the development of simple and efficient protocol for the synthesis of quinolines has been the subject of continued interest from the several decades.…”

“…The other alternative methods for the 35 synthesis of quinolines by transition metal-catalyzed process were also reported in the literature. Some research groups have reported the rhodium complex catalyzed reaction of aniline with aliphatic aldehyde, 18 aliphatic olefin, 19 styrene, 20 and the reaction of nitrobenzene with aliphatic alcohol 21 24 Co, 25 and Fe 26 were also developed for the quinolines synthesis. Despite the advances in methodology for 50 the quinoline synthesis, most of the reported protocols have one or more shortcomings such as use of hazardous organic solvents, harsh reaction conditions, limited functional-group tolerance and the homogeneous non-recyclable catalytic system which has the problem of catalyst-product separation thereby limits the 55 attractiveness of these transformations for their general applications.…”

Transition Metal‐Catalyzed Directing‐Group‐Assisted C−H Activation of Phenols

“…Only af ew methodsh ave been reported in the past few decades for transition-metal-catalyzed highly regioselective para-selective CÀHf unctionalization of phenolst hrough aF riedel-Crafts-type reaction. [61] Regarding direct CÀHa ctivation,i n2 016, Maiti and co-workers designed an itrile-containing silyl-biphenyl template, in which the silicon atom connected the hydroxy group, andt he nitrile group coordinated to aP dc atalyst (Scheme 49). [62] The intriguing biphenyls caffold guaranteed the CÀHa ctivationt oa ccurately occur at the para position through formation of al ess strained seventeen-membered palladacycle intermediate (126)a nd fine-tuning of the length of the template.…”

ChemInform Abstract: Highly Active Palladium‐Based Catalyst System for the Aerobic Oxidative Direct Coupling of Benzene to Biphenyl.

“…During the reaction, ah omogeneous solutioni so btained with acetic acid, whereas ab iphasic system forms using aqueous acetic acid solution, the upper phase of which is benzene and the bottom phase is water.T he composition of the aqueous acetic acid solution affects the acidity/basicity andt he solubility of the substrate, catalyst, and products significantly,f rom which the mixed solventi nfluences the mass transfer across the phase and the accessibility of the catalytic speciest ot he substrate, and ultimately results in ad ifferent catalytic performance. [39,40] Besides, the additiono fw ater will promote the slow elimination of H + + from the Wheland intermediate, the control step in the formation of biphenyl, which thus enhances the reaction. [21] Nonetheless,t oo much water will decrease the benzene solubility in the catalytic phase dramatically,w hich thus causes ad ecrease in the reactivity.N op roduct forms in pure water because of the immiscibilityo fb enzene and Pd(OAc) 2 in water.…”